1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to noise reduction in an image sensor, and more particularly, to estimating noise determination criteria in an image sensor.
2. Description of the Related Art
As well known in the related art, an image sensor is a device for reproducing an image based on photo-reactive properties of a semiconductor. Such an image sensor is constructed of small photodiodes (e.g., pixels), and processes information on light to which the photodiodes respond.
Such a pixel detects the brightness and wavelength of light emerging from each object, reads them in electric values, and converts them into a level that can be signal-processed. That is, the image sensor is a semiconductor device which converts an optical image into electric signals, and various portable electronics such as a digital camera and mobile communication terminal equipped with such an image sensor have been developed and distributed in the market.
When an image sensor takes a picture image of an object, the image has noise. However, it is difficult to remove or reduce such noise by applying noise determination criteria indiscriminately since noise or elements that may be discerned as noise are variable according to images. Noise determination criteria applied indiscriminately may determine and remove texture information erroneously as noise. Likewise, noise may be determined as texture information, and thus an image with the noise may be used. Accordingly, there is required a noise estimation method that can variably determine noise according to images.